Various studies have shown that one of the sources of motor vehicle radio frequency interference radiation is the breakdown of the arc gap between the distributor rotor output segment tip surface and each of the circumferentially disposed distributor output terminals. Laboratory observations indicate that the radio frequency interference generated across this arc gap is substantially reduced with a reduction of breakdown potential level. These laboratory observations further indicate that excessive radio frequency interference radiation is produced when the breakdown potential of this arc gap exceeds a level of the order of twelve kilovolts. It has been found that the breakdown potential level required to break down this arc gap is substantially reduced by the application of a silicone varnish material to the rotor output segment in the vicinity of the output tip surface thereof that extends substantially parallel to the axis of rotation of the rotor body member and which, while the rotor segment is rotated with the body member, traces a circular path radially inwardly from the circumferentially disposed distributor output terminals by a predetermined arc gap. It has also been found that a simple and efficient method for applying the silicone varnish material to the rotor output segment is to completely immerse the segment in a bath of the silicone varnish material whereby the segment is completely coated. As the silicone varnish material is an electrical insulator, a method for quickly and easily establishing an electrical connection between the silicone varnish coated ignition distributor rotor output segment and another ignition distributor member to which it must be electrically connected is desirable.
It is, therefore, an object of this invention to provide an improved radio frequency interference radiation suppressing ignition distributor rotor having a silicone varnish coated distributor rotor output segment.
It is another object of this invention to provide a method for establishing an electrical connection between a silicone varnish coated ignition distributor rotor output segment and another ignition distributor member to which it must be electrically connected.
It is another object of this invention to provide a method for establishing an electrical connection between a silicone varnish coated ignition distributor rotor output segment and another ignition distributor member to which it must be electrically connected in overlap engagement by electrically rupturing the silicone varnish material located between the respective surface overlap areas of the silicone varnish coated rotor output segment and the other member.
It is another object of this invention to provide a method for manufacturing an ignition distributor rotor that suppresses radio frequency interference radiation.